1. Field of the Invention
The present invention relates to an electrothermal heating device provided with a box-shaped plug socket provided with a socket-side electroconductive part electrically connected to an electrothermal heater and with an opening, and a power source plug provided with a plug-side electroconductive part electrically connectable with the socket-side electroconductive part, the plug being insertable into and removable from the plug socket via the opening.
2. Description of the Related Art
Examples of such electrothermal heating device include heated cooking appliances (hotplates, meat grills, grill pans, Japanese takoyaki makers, etc.), electric pots, electric kettles, humidifiers, and other electrothermal heating device provided with an electrothermal heater. Such electrothermal heating device are configured so that electrical power from a power source is supplied to the electrothermal heater via the power source plug inserted in the plug socket, and heat generated by the electrothermal heater heats an object to be heated.
For example, in the heated cooking appliances constituting examples of electrothermal heating device disclosed in patent documents 1 and 2, a power source plug provided with a plug-side electroconductive part electrically connected to a power source is inserted into a box-shaped plug socket provided with a socket-side electroconductive part electrically connected to an electrothermal heater via an opening in the plug socket. When the power source plug is inserted in the plug socket, the plug-side electroconductive part and the socket-side electroconductive part are electrically connected, and electrical power from the power source is supplied to the electrothermal heater. A cooking plate constituting an object of heating, the plate being disposed near the electrothermal heater or in contact with the electrothermal heater, is thereby heated, and a food product of the like can be placed upon an upper surface of the cooking plate and cooked by heating.
In these heated cooking appliances, the box-shaped plug socket is attached to a side surface of the cooking plate, and a pair of electroconductive pins (an example of a socket-side electroconductive part) constituting a connecting terminal of the electrothermal heater, integrally formed with the cooking plate are formed so as to project horizontally from the side surface of the cooking plate towards the opening of the plug socket when positioned within the plug socket. A closing plate for closing the opening of the plug socket shut when the pair of electroconductive pins is positioned within the plug socket is provided.
In the heated cooking appliance disclosed in document 1, the closing plate is rotatable around a rotational shaft provided at one end of the closing plate, and, in its natural state, is drawn in a closing rotational direction closing the opening of the plug socket by a biasing spring so as to close the opening. The closing plate is provided with an opening force receiving part at a location closer to one end than the rotational shaft for receiving pressure in an insertion direction from a heat-sensitive post of the power source plug and rotating the closing plate around the rotational shaft in an opening rotational direction opposite to the closing rotational direction. The heat-sensitive post thereby presses the opening force receiving part in the insertion direction as the power source plug is inserted into the plug socket, and the closing plate is rotated in the opening rotational direction around the rotational shaft in opposition to the biasing force of the biasing spring, causing the opening to open. With the opening thus in an open state, the power source plug is inserted into the opening of the plug socket.
Meanwhile, in the heated cooking appliance disclosed in document 2, the closing plate is disposed so as to close the opening in a position entering beyond the opening into the plug socket. The closing plate is slidable in a sliding direction that is the same direction as the direction in which the power source plug is removed from the plug socket, and, in its natural state, is urged by the biasing spring in the sliding direction towards the opening, and is disposed in contact with a guide part formed projecting inward within the plug socket. The closing plate is also provided with a contacted surface orthogonal to the sliding direction, and is configured so that, as the power source plug is inserted into the plug socket, a contacting surface formed on the power source plug orthogonally to the insertion/removal direction and the contacted surface come into contact, and are slidable in the sliding direction while resisting the pressing force of the biasing spring. The closing plate being made to slide in the sliding direction by the power source plug in this way causes the power source plug to be inserted into the opening of the plug socket.